1. Field
The present invention relates generally to wireless power transfer, and more specifically, to systems, device, and methods related to security of an energy storage device.
2. Background
Approaches are being developed that use over the air power transmission between a transmitter and the device to be charged. These generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and receive antenna on the device to be charged which collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas. So charging over reasonable distances (e.g., >1-2 m) becomes difficult. Additionally, since the system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g. mms). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically small, hence the user must locate the devices to a specific area.
The latest portable electronic devices combine various capabilities, such as capabilities of a cell phone, a media player, and a laptop computer. A downside of this much capability in single device is that the battery is drained quickly requiring frequent recharge. It is desirable to recharge these devices in public places, such as airports, shopping malls and coffee shops. It is also desirable for the user to be able to move about the public places while the device is recharged. Further, it is desirable to secure the battery while it is being recharged. This could be accomplished by physical security at the kiosk, but this scheme is prone to circumvention by physical means and places the liability on the owner of the kiosk.
A need exists for methods, systems, and devices to enhance security of removable, rechargeable batteries. More specifically, a need exists for methods, systems, and devices for enhancing the security of a battery being charged in a public battery charger.